Boom lift



Sept. 7, 1965 a. w. M ININCH ETAL 3,204,474

BOOM LIFT Filed July 23, 1962 2 Sheets-Sheet l INVENTORj'. z% w BY 4/ #41! W Sept. 7, 1965 Filed July 25, 1962 G. w. MCININCH ETAL BOOM LIFT 2 Sheets-Sheet 2 United States Patent 3,204,474 BOOM LIFT Glenn W. Mclniuch, Omaha, and Donald F. Rosterman, Auburn, Nebn, assignors to Auburn Machine Works, Inc., Auburn, Nebn, a corporation of Nebraska Filed July 23, 1962, Ser. No. 211,646 4 Claims. (Cl. 74-109) This application relates to trencher attachments for tractors and like vehicles and, more particularly, to power-actuated boom lifts therefor.

In the performance of many operations with a boom attachment, and particularly in the case of vehiclemounted trenching equipment, it is desirable to be able to raise and lower the boom rapidly through a relatively large arc. One method presently employed for raising and lowering booms includes hydraulic actuators working directly against certain boom elements or connected thereto by roller chains or the like. However, such constructions require a relatively long stroke of the actuator to achieve a relatively short rotational arc of the boom, and are inherently expensive. Also, prior constructions involve heavy unbalanced loads on bearings and mounting brackets, giving rise to maintenance problems.

It is, therefore, an object of the present invention to provide an improved boom-lifting mechanism for a trencher or the like which requires a relatively small actuator stroke to obtain a rotation of the boom through a wide are.

It is another object of the invention to accomplish the above while distributing and balancing loads so as to avoid placing heavy reaction loads on the boommounting bearings and associated parts, thus effecting a saving in initial cost and maintenance.

It is also an object of the invention to provide an improved boom-lifting mechanism which is economical in construction, long wearing, efliciently lubricated, and easily inspected and serviced.

It is a related object to provide such a mechanism, which is adaptable to existing designs of trenchers and the like, with little or no change in structure.

The invention consists of the novel constructions, arrangements, and devices to be hereinafter described and claimed for carrying out the above-stated objects and such other objects as will be apparent from the following description of the preferred form of the invention, illustrated with reference to the accompanying drawings, wherein:

FIGURE 1 is a plan view of a vehicle and boom attachment embodying the present invention;

FIG. 2 is a fragmentary section of a portion of the boom-lifting mechanism of FIG. 1; and

FIG. 3 is an enlarged partial section of the boom attachment of FIG. 1.

While the invention is susceptible of various modifications and alternative constructions, one illustrative embodiment has been shown in the drawings and will be described below in detail. It should be understood, however, that there is no intention to limit the invention to the specific form disclosed, but, on the contrary, the intention is to cover all modifications, alternative con structions, and equivalents falling within the spirit and scope of the invention as expressed in the appended claims.

Referring now to the drawings, FIG. 1 shows a tractor generally at having a boom attachment 11 secured at the rear thereof to an auxiliary frame, indicated at 12. Although a trenching boom having a digger chain 13 is illustrated, it will be appreciated that the present invention has utility in the performance of a variety of operations requiring a boom of similar character.

The boom attachment comprises a boom 15 which terminates in a yoked end 16 having a pair of mounting legs 17 and 18. The boom is adapted to swing or pivot about an axis near the end thereof, and, accordingly, trunnions are provided in the form of sleeves 22, 23 fitted into apertures 20 and 21 in the respective legs of the boom, and are keyed, welded, or otherwise secured, against rotation. For journaling the trunnions with respect to the frame of the vehicle, aligned bearings, here indicated in the form of pillow blocks 25 and 26, are provided which are bolted or otherwise secured in place. Both bearings are provided with fittings 30 for the periodic introduction of grease to the bearing area.

In accordance with the present invention, the boom is raised and lowered through a novel, power-actuated planetary type gearing arrangement 33 including a sun gear directly coupled to the boom, a set of cooperating reaction or planet gears secured with respect to the tractor frame, and a ring gear rocked by a hydraulic actuator and meshing with the planet gears to achieve multiplied angular movement of the sun gear. Thus, the gear train 33 includes a sun gear 35, a set of three reaction or planet gears 37 arranged in equally spaced relation about the sun and in mesh therewith, and a ring gear 39 which has internal teeth in mesh with the planets 37. p

The sun gear 35 is secured against lateral and rotational movement in any suitable manner, such as a key 40, to the trunnion 23 fitted to the leg 18 of the boom. The planets 37 are secured relative to the frame in order that they may serve as reaction elements for the gear train. To facilitate mounting and positioning of the planet, a transverse backing plate 41 is formed integrally with the pillow block 26. The planets are journaled on stub shafts 43, which are mounted in holes 44 in the backing plate 41.

It is an attribute of the present arrangement that rotative power provided by a fluid actuator 45, which has a linear stroke, is converted to rotation of the ring gear 39 and multiplied by the planetary gear arrangement to rotate the boom about the trunnions. In this manner, a stroke of the actuator required to rotate the ring gear through an arc approximating results in an arc of approximately traversed by the boom. The precise ratio of movement by the actuator and the boom is a function of the number of teeth on the ring gear and the sun gear, respectively.

By so arranging the planets about the sun, further benefits are derived from the system. Thus, the reaction forces which are absorbed by the planets are not only balanced about the gear train, but are evenly distributed among the planets so that no one bearing member carries the full, or a disproportionately large, reaction. More than the three planets shown may be provided, of course, in the event that greater reaction loads make an increased number desirable.

The planetary gear arrangement 33 is housed within an enclosure formed by the backing plate 41, the ring gear 39, and an annular face or cover plate 46 fastened by bolts 47 to the ring gear. Thus, the ring gear, which is adapted to be rotated about the sun gear, is formed with a laterally extending portion 50 which engages the peripheral edge 51 of the backing plate 41. An O-ring seal 52 is provided in a groove formed on the peripheral edge 51 of the backing plate and is compressed by the extending portion of the ring gear 39. A fluid seal is thereby formed while permitting the ring gear to be rotated on the backing plate. In a like manner, a fluid seal of any suitable type, such as O-ring 53, is provided between the cover plate 46 and the trunnion 23, upon which it rotates. An additional seal,'such as O-ring seal 54, is provided in the pillow block 26 to prevent the entry of heavy grease into the planetary set. The trunnion 23 extends beyond the cover plate a suitable amount so as to provide a restriction-free land 55, and it is a further feature of the present invention that inspection, timing, maintenance, and repair of the planetary gear train are easily accomplished by sliding the cover plate 46 and ring gear off the backing plate and along the land, thereby gaining access to the gear train. During normal operation, however, a clip ring 57 is provided, which fits in a groove formed in the trunnion for retaining the cover plate in position to provide an oil-tight casing in which the gear train may function fully lubricated.

In order to enhance lubrication of the gears, the internal surface of the faceplate 46 is provided with a plurality of oil pockets 59, defined by laterally extending ridges 60 which are also conveniently spaced to present a holding surface for the planet gears 37. Thus, when the faceplate is in position, the ridges 60 are in bearing contact with the planet gears, thereby holding them in alignment with the sun and ring gears Without requiring additional fastening devices and, at the same time, the oil pockets provide lubricating oil at the gears rotating on the stub shafts 43. By arranging the elements so that the planets need not be fastened to the shaft, servicing of the planetary gear set is further eased. Since the reaction load of the system which is carried by the planet gears makes bearing surfaces susceptible to Wear, the present construction makes it extremely simple to inspect and/ or replace the planets by pulling them laterally outward from their respective stub shafts 43, with the faceplate moved to its service position. The unit also is timed, i.e., the boom and actuator positioned with one another to give the desired working relation, by removing the planets and positioning the boom and actuator at a reference position, and replacing the planets. This is quickly accomplished by merely sliding the faceplate back and positioning the planets as previously indicated.

The ring gear is connected with the fluid actuator 45 as the systems source of power and is, therefore, provided with a trunnion housing 62 carrying a bearing 63 on its periphery for receiving fluid plunger 65 of the fluid actuator 42. The plunger 65 is screwed into a curved mounting arm 66 having an aperture 67 therein. A pin 69 connects the arm 66 and trunnion housing 62. The curvature of the arm permits a longer effective stroke of the plunger which rotates the ring gear. By actuating the plunger 65, the ring gear 39 is rotated through a determinable, though relative short, are. Such rotation causes a reverse rotation of the planets 37 on the stub shafts 43, which absorb the reaction forces. The rotating planets drive the sun gear to rotate the boom on its trunions. The are subtended by the sun gear is in inverse proportion to the number of teeth on the ring gear as compared to the sun gear, and is, therefore, substantially larger than the arc traversed by the ring gear.

The present invention provides for driving the digger chain, as indicated in FIG. 3. Thus, a jack shaft 71 is provided, journaled by roller bearings 72 and 73 in the hollow trunnion 23. Sprockets 75 and 76 are secured to either end thereof, the sprocket 75 being aligned with the boom 15 for driving a digger chain 13 or the like while the sprocket 76 is driven by the power take-off 78 of the vehicle, as indicated in FIG. 1.

We claim as our invention:

1. An attachment for a tractor or the like including, in combination, an elongated boom, means at one end thereof for mounting said boom to said tractor in bearing relation, and means for raising and lowering said boom, including a gear train having a ring, reaction, and sun gears, and a hydraulic actuator, said sun gear being connected to said boom, said reaction gears being fixed with respect to said tractor; said hydraulic actuator having one end fixed with respect to said tractor and the other pivotally attached to said ring gear, whereby a relatively small movement of said actuator imparts a relatively large movement to said boom.

2. An attachment for a tractor, or the like, including, in combination, an elongated boom, trunnions at one end thereof, bearing means on said tractor for journaling said trunnions and power-actuated means for raising and lowering said boom, including a gear train having a sun gear mounted on said trunnion, reaction gears in mesh with said sun gears, and a ring gear meshed with said reaction gears rotatable about said sun gear, a hydraulic actuator for rotating said ring gear, a backing plate rigid with respect to said tractor for positioning said reaction gears, said ring gear being received about said backing plate in fluid-sealing relation, a cover plate rotatably mounted on said trunnion and secured to said ring gear, said backing plate, ring gear, and cover plate together defining a housing for said gear train, and a land on said trunnion adjacent said cover plate, said cover plate and ring gear adapted to be move-d along said land and away from said backing plate to gain access to said gear train for maintenance thereof.

3. An attachment for a tractor, or the like, including in combination, an elongated boom, trunnions at one end thereof, bearing means on said tractor for journaling said trunnions and power-actuated means for raising and lowering said boom, including a gear train having a sun gear mounted on one said trunnion, reaction gears in mesh with said sun gears, and a ring gear meshed With said reaction gears rotatable about said sun gear, a hydraulic actuator for rotating said ring gear, a backing plate rigid with respect to said tractor, transverse stub shafts secured in said backing plate for receiving said reaction gears, said ring gear being received about said backing plate in fluid-sealing relation, a cover plate rotatably mounted on said one trunnion in fluid-sealing relation, and secured to said ring gear, said backing plate, ring gear, and cover plate together defining a housing for said gear train, said cover plate being constructed to hold said reaction gears on said stub shafts while providing lubrication thereto, and a land on said trunnion adjacent said cover plate, said cover plate and ring gear adapted to be moved along said land and away from sid backing plate to gain access to said gear train for maintenance thereof.

4. In a device having an elongated boom mounted with respect to a fixed member for vertical movement about said mounting and having means for effecting movement of said boom comprising, in combination, a motion-multiplying gear set having a sun gear, reaction gears, and an associated reaction gear carrier, and a ring gear, said sun gear being fixed with respect to said boom, said reaction gear carrier being fixed with respect to said stationary member, and an actuator interconnecting said ring gear and said stationary member and adapted to rotate said ring gear with respect to said sun gear in such a manner that a relatively short movement of said actuator imparts a relatively large rotational movement to said boom with respect to said stationary member for raising and lowering the same.

References Cited by the Examiner UNITED STATES PATENTS 1,444,908 2/23 Fulton 7 4-39l 2,252,967 8/41 Forton 14807 2,725,996 12/55 Britton 212-66 X 3,035,722 5/62 Anderson et al. 2l2-35 X FOREIGN PATENTS 677,439 8/52 Great Britain. 868,370 5/ 61 Great Britain.

BROUGHTON G. DURHAM, Primary Examiner. 

1. AN ATTACHMENT FOR A TRACTOR OR THE LIKE INCLUDING, IN COMBINATION, AN ELONGATED BOOM, MEANS AT ONE END THEREOF FOR MOUNTING SAID BOOM TO SAID TRACTOR IN BEARING RELATION, AND MEANS FOR RAISING AND LOWERING SAID BOOM, INCLUDING A GEAR TRAIN HAVING A RING, REACTION, AND SUN GEARS, AND A HYDRAULIC ACTUATOR, SAID SUN GEAR BEING CONNECTED TO SAID BOOM, SAID REACTION BEARS BEING FIXED WITH RESPECT TO SAID TRACTOR; SAID HYDRAULIC ACTUATOR HAVING INE END FIXED WITH RESPECT TO SAID TRACTOR AND THE OTHER PIVOTALLY ATTACHED TO SAID RING GEAR, WHEREBY A RELATIVELY SMALL MOVEMENT OF SAID ACTUATOR IMPARTS A RELATIVELY LARGE MOVEMENT TO SAID BOOM. 